Gas blast circuit breaker



sept. 8 1970 1 JAlLLE-r GAS BLAST CIRCUIT BREAKER Filed DeC. 26, 1967 Fig.1

United States Patent Oice 3,527,912 Patented Sept. 8, 1970 67 Int. Cl. H01h 33/ 88 U.S. Cl. 200--148 13 Claims ABSTRACT OF THE DISCLOSURE A puffer type electrical circuit breaker having gas blast arc extinguishing means operable to delay the release of the gas blast until a time after the contacts have moved a certain distance apart from each other.

The present invention relates to a puffer type gas blast circuit breaker wherein a blast of gas directed towards the region between the contacts causes the extinction of the arc drawn between separating contacts.

In known circuit breakers of this type, the gas blast is initiated at the very moment that the contacts start to move apart. This has two disadvantages: one being that such early blowing is superfluous in that it has no effect in extinguishing the arc while the contacts are still very close to each other; and the other being that if the pressure of the gas blast is generated by the circuit breaker itself, such early release of the gas causes its pressure to drop prematurely so that only a reduced gas pressure is subsequently available at the time that the gas blast is really needed for blowing out the arc.

It is an object of this invention, therefore, to realize a gas blast `arc extinguishing means for a circuit breaker wherein the gas blast pressure is self-generated by the breaker and wherein said -blast is not initiated until after the contacts have moved apart a certain extent.

It is a further object of this invention to realize the foregoing through an arrangement iwhich is simple and economical to construct and which is highly reliable in operation.

Still another object of the invention is to realize a pufer type circuit breaker comprising a safety device preventing dangerous pressure build-up of the compressed gas during the opening movement of the contacts.

Other objects of the invention are those which are inherent in the invention as disclosed herein.

Generally, the foregoing objects are realized through an arrangement wherein the breaker contacts are enclosed within a nozzle-like orifice member which moves together with the movable contact during the opening movement thereof, whereby the exhaust opening is closed by a valve member movable together with the orifice member only for a limited extent of the travel thereof whereupon the valve member opens thereby initiating the flow of the compressed gas after the contacts have moved apart a certain extent.

The device in accordance with the present invention makes it possible to obtain blast pressures which are comparable to those of compressed gas circuit breakers without requiring a separate source of compressed gas. It can furthermore easily be applied to any type of break-arcblast circuit breaker and in particular to hermetic cartridge circuit breakers, or circuit breakers having a closed casing lled with gas, such as sulfur hexafiuoride. An embodiment of the invention will be hereinafter given by way of example with reference to the attached drawings.

FIG. 1 is an axial section through a circuit breaker in accordance with the invention representing the apparatus in closed position;

FIG. 2 is a similar view showing the position of the parts just before the opening of the blast plug;

FIG. 3 shows the circuit breaker in open position.

An insulating enclosure or arc extinction chamber is formed by cylinder 10i, one of the ends 11 of which is traversed by a sliding control rod 12 which is rigidly connected to a moving contact 13 which cooperates with a semi-fixed contact 14. The moving contact 13 is surrounded by a nozzle shaped orifice member 1S of insulating material or for instance of graphite, at one end of which there is positioned a piston 16 which slides in the cylinder 10| and which is rigidly connected with the control rod 12. The piston 16 whose periphery slides on the inner wall of the cylinder 10 is provided with apertures 17 which place the interior of the orifice member 15 in communication with the lower part of the cylinder 10 which in turn communicates with the exterior of the cylinder through openings closed by one-way flaps 18 which permit fluid flow into the cylinder but not discharge outwardly therefrom. A iiuid seal such as lip seal means 19 is provided between the rod 12 and the cylinder end wall. Said means 19 could, for example, be an elastic material and could be a part of the same member which comprises the flaps 18. At end of rod 12 externally of cylinder 10 is electrically connected to a stationary terminal 21 through a linkage system 20, said rod 12 being reciprocally actuated by a not shown control device.

The blast nozzle 15 which constitutes an arc extinguishing chamber can be of any customary shape but it is advantageous for it to include a convergent-divergent section having a throat 22 positioned downstream of the end of the movable contact 13 whereby the two contacts are on opposite sides of the throat 22 after said contacts separate from each other. The end of orifice member 15 opposite to puffer piston 16 includes a seat for a valve or closure member 23 which, when seated, seals the interior of orifice member 15 from the portion of cylinder 10 above piston 16. Valve member 23 is axially guided by rod 24 which may conveniently serve as a conductor from contact 14 to externally of the cylinder.

A compression spring 25 positioned between the valve member 23 and a xed part of the cylinder 10 serves to bias the valve member 23 into seated position relative to the orifice member 15, said valve member 23 being axially slidable along the length of guiding rod 24. The downward stroke of member 23, however, is limited by any convenient means such as, for example, a shoulder 26 along the extent of rod 24. The semi-stationary contact 14 is connected in suitable fashion, for instance by a conductor 27 and a lead-through member 28, to the opposite terminal 29 of the circuit breaker, the conductor 27 being flexible in the case of a contact of semi-stationary type.

The rod 24 bearing the semi-stationary contact 14 slides in a support 24' spaced from and borne by the end of the cylinder 10, its stroke in the direction of the moving contact 13 being limited by a shoulder on the rod 24 which strikes against the support 24'. A compression spring 27 which rests for instance against said shoulder and is inserted between said shoulder and the end of the cylinder urges the rod 24 and the semi-stationary contact 14 towards the moving contact 13 in such a manner that said semi-stationary contact 14 follows the movement of the moving contact 13 at the start of the opening stroke until the shoulder of the rod 24 strikes against the support 24. The portion of cylinder 10 above piston 16 communicates to exteriorly of the cylinder through apertures 30.

The operation of the circuit breaker is as follows:

When the contacts '13 and 14 are in their normal closed position (FIG. 1), the respective cylinder portions on each side of piston 16 are both at the same pressure, namely: atmospheric pressure, and the closure member 23 is maintained in its sealed (sealing) position relative to the orifice member 15 by the spring 2S. When it is desired to break the circuit by opening the contacts 13 and 14, the not shown control means is actuated whereby the rod 12 begins a downward movement carrying with it the Contact 13. During the initial phase of this downward movement, the contact 14 follows the contact 13 since rod 24 is axially movable to a limited extent as heretofore described. Further, since piston 16 and orifice member 15 are both rigidly attached to rod 12, the downward movement of said rod 12 brings about a compression of the gas in the lower putter part of cylinder caused by the rapid movement of piston 16.

Continued downward movement of the rod `12, however, results in the separation of the contacts 13 and 14 from each other as soon as the rod 24 is stopped axially by stationary support 24', the rod 12 continuing to move downwardly (FIG. 2) while closure member 23 slides along rod 24 and remains in seated (sealed) position relative to orifice member 15. Meanwhile, the gas pressure in the puffer portion of cylinder 10 is progressively increased to a maximum. This pressure increase is not only the result of volumetric compression of the gas but is also the result of a heating thereof occasioned yby the arc which flashes across the contacts 13 and 1-4 as they separate from each other, this arc being symbolized by the crooked arrow in FIG. 2. In fact, if the members proximate to the arc (such as valve 23 or orifice member 15) are made of materials which themselves liberate gas during the occurrence of the arc, this gas liberation further enhances the increasing of pressure within the lower portion of cylinder 10.

When the gas pressure in the putter portion of cylinder 10 is such as to exert a greater force upon closure member 23 than the force exerted thereon by spring 2'5, said member opens (FIG. 3) whereby a rush or blast of the com-pressed gas occurs past the convergent section 22 and through the upper end of orifice member which previously had ybeen closed by member 23. This blast of gas, as is evident in FIG. 3, follows a fiow pattern which extends along the direction of the arc which bridges from one contact to the other, and the are is literally blown out by the gas blast. The gas vents to atmosphere through vent holes 30 when the contacts are subsequently closed again and pursuant to upward travel of orice member 15 and piston 16, fresh gas is drawn into the lower portion of cylinder 10 past the iiaps 118.

The moment that closure member 23 separates from orifice member 15, is determined by the force of the spring 25. This pressure may be very substantial and reach values comparable to those existing in compressedair circuit breakers. In accordance with another embodiment, the opening of the member 23 is caused by the member 23 coming against the shoulder 26 of the rod 24 (see FIG. 2) whereby member 23 is axially stopped although orice member 15 continues its downward travel. According to this second embodiment, the closure member 23 opens at a particular point in the downward travel of the contact 13 regardless of whatever may be the level `of pressure in the lower portion of cylinder 10. In this case, the spring 25 constitutes a safety device which permits the opening of the plug 23 in case of accidental excessive pressure in the lower portion of the cylinder 10.

Various details presented herein relative to specific embodiments of realization are merely illustrative and not limitative of the applicability of the herein disclosed inventive concept. The device in accordance with the invention can be applied with the same advantages inter alia to hermetic enclosure circuit breakers. It is then merely necessary to provide a communication, having a nonreturn valve, between the upper part and the lower part of the said cylinder to replace the orifices 17, the orifices 18 and 30 remaining closed. In this case the blast fluid can be any suitable fluid and in particular an electronegative gas such as sulfur hexauoride.

What is claimed is:

1. A pufier type circuit breaker comprising separable contact means to drawn an arc, a movable elongated orifice member having openings at opposite ends thereof, said contact means being positioned Within said orifice member, puffer means to compress a gas in a pufer cylinder in response to the separation movement of said contact means, the interior of said orifice member being in communication with the interior of said puffer cylinder whereby compressed gas is fed from the latter to the former along a fluid flow path from said putter means and along the arc gap created ybetween said contact means, when the latter are in separated position, a closure means normally blocking said path but being sensitive to pressure conditions in said ori-tice member to unblock said path automatically pursuant to the pressure in said orifice member reaching a predetermined magnitude after drawing of said arc.

2. The circuit breaker of claim 1, said orifice member being secured to a pufer piston and, a circumferential portion of said putter piston being slidingly sealingly engaged with the wall of said puier cylinder, an axially displaceable closure member sealingly engaged with one end of said orifice member, said orifice member being integrally movable together with a first contact of said contact means, a resiliently yieldable -means urging said closure member into sealing engagement with said one end of the said orifice member, said closure member being axially displaceable to follow the axial movement of said orifice member but being automatically displaceable away therefrom so as to unseal said orifice member one end in response to the pressure in said orifice member reaching a predetermined magnitude.

3. The circuit breaker of claim 2, including stop means to limit the extent of axial displacement of said closure member in following said orifice member.

4. The circuit breaker of claim 1, said contact means comprising a second Contact being axially movable to a limited extent together with said first contact in the direction ywhich corresponds to said first contact moving away from said second contact.

5. The circuit breaker of claim 2, said orifice member having a convergent-divergent section in the direction of said fiow path, said contact means being positioned within said orifice member whereby upon separation of one from the other they are respectively positioned on opposite sides of the throat of the convergent-divergent section.

6. The circuit breaker of claim 4, including an elongate guide member axially reciprocable along the axial direction of displacement of said first contact, said second contact being integrally movable with said guide member, means to restrict the axial displacement of said guide member, said closure member being slidably mounted on said guide member for axial displacement relative thereto, said resiliently yieldable means urging said closure member in one axial direction along said guide member, and including means to restrict the axial displacement of said closure member along said guide member.

7. A putter type circuit breaker comprising an axially movable elongated orifice member, separable contact means to draw an arc in said orifice member, puffer means to compress an arc extinction gas in response to said axial movement of said orice member during the separation movement of said contact means, an axially movable closure member cooperating in sealing relation with one end of said orifice member, resiliently yieldable means urging said closure `member into sealing engagement with said end, guide means for said closure member adapted to cause said closure member to follow in sealing engagement the axial movement of said orifice member during the beginning of said separation movement under the action of said resiliently yieldable means, and means to limit the extent of said axial movement of said closure member in following said orifice member so as to unseal said orifice member to force a blast of said gas compressed by said puler means through said orice member and against said arc.

8. The circuit breaker of claim 7, said resiliently yieldable means being adapted to cause said closure member to unseal said orifice member in response to the pressure in said orice member reaching a predetermined magnitude after drawing of said arc.

9. The circuit breaker according to claim 7, said guide means include stop means to limit the extent of axial movement of said closure member in following said orice member.

10. The circuit breaker of claim 7, said closure member comprising a movable valve member, said guide means comprising a conducting rod traversing said valve member.

11. The circuit breaker of claim 10, said contact means comprising a first contact movable with said oriiice member and a second contact secured to said conducting rod.

12. The circuit breaker of Claim 11, comprising support means for said conducting rod permitting a small axial movement of said conducting rod under the action of spring means.

13. The circuit breaker of claim 11, said orifice member comprising an annular throat portion downstream of said 'first contact.

References Cited UNITED STATES PATENTS 2,111,416 3/1938 Balachowsky. 2,551,772 5 1951 Thibaudat. 2,935,575 4/1960 Baker.

ROBERT S, MACON, Primary Examiner U.S. C1. X.R. 200e-15() 

